140 is an odious number because it has an odd number of ones in its binary representation. The sum of Euler's totient function φ(x) over the first twenty-one integers is 140.
140 is a repdigit in bases 13, 19, 27, 34, 69, and 139.
In other fields
140 is also:
The number of varieties of ashes from different varieties of pipe, cigar, and cigarette tobacco included in the Sherlock Holmes monograph.
The former Twitter entry-character limit, a well-known characteristic of the service (based on the text messaging limit)
A film, based on the Twitter entry-character limit, created and edited by Frank Kelly of Ireland[2]